Tap Creek

The Chicago & North Western Tap Creek Branch


Step 7

Now it is time to solder the decoder wires to the light board. We will use 8 of the 10 wires. The table shows which wires, and what they are used for.


The picture below show where the wires shall be soldered to the light board.


Note that we need to attach the blue wire in two places. First cut it to length to reach the rightmost “blue” contact wire. Then cut the remaining part so that it reaches from there to the left “blue” contact point.

Do also note that the white wire is not soldered to a contact wire, but directly to the board connector at that point.

Start by reinstalling the light board into the frame. Make sure that the right-hand side motor clip really gets under the board! Then insert the decoder under the rear part of the board, as shown below.

Pick the yellow wire. Slide up over the rear end of the board and forward to its contact point. Cut it to length and solder. Then do the blue wire, then the black, and so on, working your self towards the front

The next picture shows a top view of the end result, with all the wires in place. Keep the area to the rear of the decoder (pointed at by the arrow) free of wires, or the shell will not seat properly. Do also make sure that all wires lie between the frame halves and that they do not protrude above the top of the frame.

The two unused wires (green and violet) are shortened, isolated with some heat shrink tube and left lying on top of the board. They may be used in some later project. The shrink tube on the white wire was added because its insulation got damaged.

Before reinstalling the shell, put the engine on the track and test run it. If the engine is noisy (a vibrating sound), take the frame apart again and make sure that the square “nuts” that keep the worm gear assemblies in place are mounted correctly. The smooth side of the “nuts” shall be vertically aligned (facing out towards the frame halves).

Reinstall the shell, and make sure it seats properly. Check the coupler height. If there is a problem, check the wires again, so that they do not interfere with the shell.

And that’s it!

Step 6

Now it is time to solder contact wires to the board. Keep the board with is down-side up during this process. For each hole bend the tip of a piece of wire as shown in the picture below.

I used .010” diameter brass wire, but nearly any type wire will do. The bent tip is 2 mm (.08 inches) long.

Thread the wire through the hole and let it hang straight down, resting its bent “tip” on the PC board. The bent “tip” shall rest on the contact spot near the hole. The picture below shows what it shall look line, when seen from above (note: it is the bottom side of the board that is up in this picture), with the wire resting on one of the motor contact pads.

Solder the wire to the contact spot, as shown in the next picture. Be careful to avoid solder from floating out and making contact with anything else than the intended contact spot.

Cut the wire on the other side of the board, leaving about 3 mm (.1 inches). Then bend the wire so that it runs “above” and clear of the board, as shown in the side view below.

Solder wires as shown above to the remaining six holes. When you are done with all the wires the up side of the board shall look something like this.

DZ143 Decoder in GP30

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Function/light common (+)


Forward light (-)


Rear light (-)


Left side (fireman’s) power pickup


Right side (engineer’s) power pickup


Motor (+)


Motor (-)


F1 – not used


F2 – not used